"One of the main tasks of evolutionary ecology is to characterize and explain the causes of phenotypic variation. Quantifying the relative contribution of genetic and ecological processes and their interaction is also important to predict future response of populations to human-induced environmental changes. The overall goal of the proposed research is to determine whether and to what extent two simultaneously induced new selection pressures are likely to slow or accelerate evolution relative to the case where only one selection pressure is present. In order to achieve this goal, I plan to collect extensive evidence on the nature of multivariate selection, genetic architecture, phenotypic plasticity, and evolutionary potential of Fennoscandian populations of the yellow dung fly (Scathophaga stercoraria). More specifically, the aims are 1.To compare the intensity and form of natural and sexual selection on fitness components across populations inhabiting six different locations in Fennoscandia 2.To relate the form and intensity of selection in the field with the genetic architecture of traits under selection using a laboratory quantitative genetic experiment 3.To examine changes in the potential for evolutionary responses to selection as a function of the number and intensity of stresses using a genotype by environment interaction experiment 4.To develop, parameterize and analyze a model of population and evolutionary dynamics under different predicted future environmental scenarios focusing on realistic description of ecological and genetic processes describing individual growth, survival and fitness"